Association between preoperative hydration status and acute kidney injury in patients managed surgically for kidney tumours

The purpose of this study was to investigate whether preoperative dehydration and intraoperative hypotension were associated with postoperative acute kidney injury in patients managed surgically for kidney tumours.

A retrospective analysis of 184 patients who underwent nephrectomy at a single centre was performed, investigating associations between acute kidney injury after nephrectomy, and both intraoperative hypotension and preoperative hydration/volume status. Intraoperative hypotension was defined as mean arterial pressure < 60 mmHg for ≥ 5 min. Urine conductivity was evaluated as a surrogate measure of preoperative hydration (euhydrated < 15 mS/cm; mildly dehydrated 15-20 mS/cm; dehydrated > 20 mS/cm). Multivariable logistic regression was used to evaluate associations between exposures and the primary outcome, with adjustment made for potential confounders.

Patients who were dehydrated and mildly dehydrated had an increased risk of acute kidney injury (adjusted odds ratio [aOR] 4.1, 95% CI 1.3-13.5; and aOR 2.4, 95% CI 1.1-5.3, respectively) compared with euhydrated patients (p = 0.009). Surgical approach appeared to modify this effect, where dehydrated patients undergoing laparoscopic surgery were most likely to develop acute kidney injury, compared with patients managed using an open approach. Intraoperative hypotension was not associated with acute kidney injury.

Preoperative dehydration may be associated with postoperative acute kidney injury. Avoiding dehydration in the preoperative period may be advisable, and adherence to international evidence-based guidelines on preoperative fasting is recommended.